The present invention relates to a pressure supply configuration, and, more particularly, to a configuration for an automatic selector device of a change-speed gearbox.
In a known pressure supply configuration of the type shown in German Offenlegungsschrift 27 44 286 for a change-speed gear-box of the epicyclic type, two input shafts are each torsionally connected to an associated gearbox element while the selector apparatus, in the form of frictional selector brakes, are connected to the respective gear-box element used as the reaction element in an associated gear. Whereas one drive clutch located in the force path between the engine and the input shaft remains engaged in all forward gears, the second drive clutch located in the force path between the engine and the second input shaft is only engaged in the direct gear and in the reverse gear.
The two clutch actuators and the selector actuators, together with the main pressure system, the pressure control device and also a return conduit are, in the known configuration, directly connected to a multi-path rotary selector valve. In a first position, the selector valve connects the main pressure system to one of the drive clutches and the pressure control device to two selector actuators whereas, in a second position, the main pressure system is shut off and the pressure control device is connected both to the clutch actuator of the other drive clutch and to a selector actuator.
In contrast, a basic object of the present invention consists essentially in creating a pressure supply for a change-speed gearbox of the fixed axis type such that the working pressure of the clutch actuators can be controlled independently of the working pressure of the selector actuators and vice versa.
The foregoing object of the present invention has been achieved in an advantageous manner by connecting the multi-path device to the conduit system of the selector actuators via a collecting conduit leading to the selector valves for control of the working pressure of the selector actuators, and the collecting conduit is shut off in the second position of the multi-path device.
In the pressure supply configuration of the present invention, the pressure control device is, in the first position of the multi-path valve device, connected only to selector valves, while the clutch actuator of the drive clutch is connected to the main pressure system.
Another aspect of the present invention allows its application in a two-path gearbox with a second drive clutch which is accordingly connected to the return conduit in the first position of the multi-path valve device.
According to another feature of the present invention, a third position of the multi-path valve device is also provided for the holding phase of the second drive clutch, in which position the clutch actuator of this drive clutch is supplied with main pressure and the working selector valves are supplied with controlled pressure.
Other embodiments of the present invention use a second pressure control device for the second drive clutch and pressure valves and directional valves in the pressure supply configuration.